Modern computer networks are divided up into layers. Each layer is responsible for providing some service to the layer above it, and may use the services of the layer below it. The International Standards Organization (“ISO”) defined seven layers as a standard for computer networks. The layers are defined as follows:
1. A physical layer, which is responsible for transmitting unstructured bits of information across a link;
2. A data link layer, which transmits chunks of information across a link. It handles error notification, network topology, and flow control. Ethernet, Token Ring, and FDDI are media access methods that offer the functionality defined by the data link layer;
3. A network layer, which is responsible for ensuring that any pair of systems in the network can communicate with each other;
4. A transport layer, which establishes a reliable communications stream between a pair of systems;
5. A session layer, which offers services above the simple full-duplex reliable communication stream provided by the transport layer;
6. A presentation layer, which is responsible for providing a means by which applications can agree on representations of data; and
7. An application layer, which runs applications.
This invention relates only to layer 2, the data link layer or the MAC layer. Layer 2 is the communication protocol which contains the physical address of a client or server station which is inspected by a bridge or switch. The layer 2 switch then forwards traffic based on the MAC layer (Ethernet or Token Ring) addresses. Currently, traffic flows such as such as broadcast, unknown multicast, or unknown unicast received at the switch are not isolated between ports on the switch so that every user on the same virtual local area network (VLAN) is able to see the traffic generated by another user on the same VLAN. There are currently many users, such as multi-dwelling unit or multi-tenant unit users which obtain network connectivity through layer 2 switches, which have confidentiality and security concerns and would like to prevent others from seeing their traffic.
Currently, one way to achieve complete isolation between access ports at layer 2 is to assign each user port an individual VLAN. The disadvantage of this approach is that the number of VLANs can grow considerably large as the number of user ports increase. This is also not a practical solution where a large number of switches are connected to each other as well as providing connections to home users, thereby increasing the number of VLANs dramatically. Thus, there exists a need for access port isolation that is more efficient and would allow port isolation at a layer 2 switch that belongs to the same VLAN.